From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sog-mx-4.v43.ch3.sourceforge.com ([172.29.43.194] helo=mx.sourceforge.net) by sfs-ml-1.v29.ch3.sourceforge.com with esmtp (Exim 4.76) (envelope-from ) id 1Z24g7-00089X-GC for bitcoin-development@lists.sourceforge.net; Mon, 08 Jun 2015 21:33:55 +0000 Received-SPF: pass (sog-mx-4.v43.ch3.sourceforge.com: domain of petertodd.org designates 62.13.148.110 as permitted sender) client-ip=62.13.148.110; envelope-from=pete@petertodd.org; helo=outmail148110.authsmtp.com; Received: from outmail148110.authsmtp.com ([62.13.148.110]) by sog-mx-4.v43.ch3.sourceforge.com with esmtp (Exim 4.76) id 1Z24g6-00076Y-1B for bitcoin-development@lists.sourceforge.net; Mon, 08 Jun 2015 21:33:55 +0000 Received: from mail-c235.authsmtp.com (mail-c235.authsmtp.com [62.13.128.235]) by punt16.authsmtp.com (8.14.2/8.14.2/) with ESMTP id t58LXj3Y017813; Mon, 8 Jun 2015 22:33:45 +0100 (BST) Received: from muck (bas3-cooksville17-1176329630.dsl.bell.ca [70.29.93.158]) (authenticated bits=128) by mail.authsmtp.com (8.14.2/8.14.2/) with ESMTP id t58LXbBZ065838 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO); Mon, 8 Jun 2015 22:33:40 +0100 (BST) Date: Mon, 8 Jun 2015 17:33:36 -0400 From: Peter Todd To: "Raystonn ." Message-ID: <20150608213336.GA19826@muck> References: <5574E39C.3090904@thinlink.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="LZvS9be/3tNcYl/X" Content-Disposition: inline In-Reply-To: X-Server-Quench: 0829cf47-0e26-11e5-b396-002590a15da7 X-AuthReport-Spam: If SPAM / abuse - report it at: http://www.authsmtp.com/abuse X-AuthRoute: OCd2Yg0TA1ZNQRgX IjsJECJaVQIpKltL GxAVKBZePFsRUQkR aQdMdgoUEkAaAgsB AmMbWVZeU157XWI7 bApPbwxDa0lQXgBi T01BRU1TWkFtCWBp VGx0Uh93fwZONn9y YUNkEHBTXk0pI0J6 X04BF2sbZGY1bX1N U0leagNUcgZDfk5E bwQuUz1vNG8XDQg5 AwQ0PjZ0MThBJSBS WgQAK04nCWAGAXY1 WwwLFjZnHEEIQTky IR0rJhYVGkpZKkIu PF09WFscUVcJDQlD A0BKBk5VKkIKXSsh AA8IFWIEFyVFTCsZ HgchJARBCSBTXSwQ H1NMTlkGFz9MWyoA QTlUUys2EBA1J09i OCAYOgJTegY/WRcF CRwXR1cw X-Authentic-SMTP: 61633532353630.1023:706 X-AuthFastPath: 0 (Was 255) X-AuthSMTP-Origin: 70.29.93.158/587 X-AuthVirus-Status: No virus detected - but ensure you scan with your own anti-virus system. X-Spam-Score: -1.5 (-) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain -0.0 SPF_PASS SPF: sender matches SPF record X-Headers-End: 1Z24g6-00076Y-1B Cc: Bitcoin Dev , "Patrick Mccorry \(PGR\)" Subject: Re: [Bitcoin-development] New attack identified and potential solution described: Dropped-transaction spam attack against the block size limit X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 08 Jun 2015 21:33:55 -0000 --LZvS9be/3tNcYl/X Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jun 08, 2015 at 02:14:01PM -0700, Raystonn . wrote: > > there is no memory pool cap currently >=20 > Real hardware does not have an infinite amount of RAM. Memory pool sizes= =20 > cannot grow unbounded. Some transactions with insufficient fees do get= =20 > dropped today after many hours. Actually they don't, which is an unfortunate problem with the existing mempool implementation; the only way a transaction can be removed from a Bitcoin Core mempool is through it getting mined, double-spent, or the node restarting. The protection that we have against that attack is that you need access to a lot of bitcoins to pay enough fees. With the 0.01mBTC/KB minimum relay fee and $230 USD/BTC that works out to about $2.3kUSD/GB of ram consumed, and furthermore, actually getting that many transactions to propagate over the network is non-trivial. (no, I'm not going to tell you how) The obvious solution is to cap the size of the mempool and evict transactions lowest fee/KB first, but if you do that they you (further) break zeroconf security. On the other hand, if you don't break zeroconf security an attacker can prevent reasonable fee transactions from propagating. I probably should get around to fixing this... --=20 'peter'[:-1]@petertodd.org 0000000000000000127ab1d576dc851f374424f1269c4700ccaba2c42d97e778 --LZvS9be/3tNcYl/X Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- iQGrBAEBCACVBQJVdgotXhSAAAAAABUAQGJsb2NraGFzaEBiaXRjb2luLm9yZzAw MDAwMDAwMDAwMDAwMDAxMjdhYjFkNTc2ZGM4NTFmMzc0NDI0ZjEyNjljNDcwMGNj YWJhMmM0MmQ5N2U3NzgvFIAAAAAAFQARcGthLWFkZHJlc3NAZ251cGcub3JncGV0 ZUBwZXRlcnRvZC5vcmcACgkQwIXyHOf0udxJaAf8DPd+WNieLQpzKNN/W2FgWCAO dM0oUlUZ3enB8y7w64pnz/ICrcyPlJD2lcPQWrAJ7WKbZpMvg2vCD2X/IOWl4GIy yIZ+xdRhw393032ox0g5c0aP/g5ll/kmR6Au9H3zZWKflrUrEdjMad/GE8112pEs J9rQeiG295VebhakgdezUavJkQRP9l0lEhKx6bbk+Br4xPoDuE3q24QT72qBR+1p hoTrerW+k4ddbEV/qhrpmR2QlRV9J6H7nqFv5GA7m/9qD+AHX3Rr/Ie/Hy5GKAx+ eewH7YFcH6J+saFpb6cWROWY4r85ElpHNFR0WG9TGpqZggaia4bF/IRmyhQWDg== =gb4z -----END PGP SIGNATURE----- --LZvS9be/3tNcYl/X--